The exemplary embodiments relate to a rear-projection type projector to display an image by scanning a screen with a laser beam.
In the related art, a rear-projection type projector to display an image by scanning a screen with a laser beam has been described. Since this related art projector can display perfect black by stopping the supply of the laser beam, it can perform display with higher contrast compared to a projector using liquid crystal light valves, for example. Further, since the laser beam has high directivity, the projection system can be simplified. Accordingly, the projector can be made compact and simple. Further, colorization may be easy by combining a plurality of laser beams of red, green, blue, etc. Additionally, color display with high color purity can be performed because of high monochromaticity of the laser beams.
However, in the case where a laser beam is used to display an image, sufficient consideration must be paid for safety so that the laser beam may not accidentally directly enter an eye of an observer. A related technology for a safety mechanism of a projector, is described in Japanese Patent Application Publication 2002-6397 (JP 2002-6397).
The technology described in the publication JP 2002-6397 includes blocking a laser output when a sensor detects the presence of an object near a projection lens. However, it is conceivable that a laser beam with high intensity may be output to the observer due to failure of the sensor because of an unexpected external cause, or failure of output control circuit of the laser beam, or the like.